Keywords:

Alectoris chukar;

biodiversity hotspots;

ecotone;

Estimator in a Dependent Sample (EDS);

morphological diversity

Summary

1

Areas of environmental transition (i.e. ecotones) have recently been shown to play an important role in the maintenance of genetic diversity, divergence and in speciation processes. We test the hypothesis that ecotone populations maintain high phenotypic diversity compared to other populations across the distribution range.

2

Focusing on the chukar partridge (Alectoris chukar Gray), we study trends in morphological diversity across a steep ecotone within the species native range in Israel and Sinai. Using 35 traits and 23 ratios between traits, we apply a novel weighted average statistic that we term ‘Estimator in a Dependent Sample’ (EDS). This estimator enables us to compare levels of diversity across populations using multiple-correlated traits and is especially useful when sample sizes are small.

3

We provide a program for calculating the EDS and a bootstrapping procedure to describe its confidence interval and standard deviation. This estimator can be applied widely in a range of studies using multiple-correlated traits in evolutionary biology, ecology, morphology, behaviour, palaeontology, developmental biology and genetics.

4

Our results indicate that within-population diversity peaks in chukar populations located in the Mediterranean-desert ecotone in Israel. However, had we not included the ecotone region in our study, we would have drawn different conclusions regarding patterns of morphological diversity across the range. We suggest that ecotones should be given higher priority in future research and conservation planning, potentially serving as within-species diversity hotspots.